package dynamicprograming;
// 63. 不同路径 II
public class LeetCode63 {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        // 行数
        int m = obstacleGrid.length;
        // 列数
        int n = obstacleGrid[0].length;
        int[][] dp = new int[m][n];
        //如果在起点或终点出现了障碍，直接返回0
        if (obstacleGrid[m - 1][n - 1] == 1 || obstacleGrid[0][0] == 1) {
            return 0;
        }
        // 初始化，遇到障碍物就跳过
        for (int i = 0; i < m && obstacleGrid[i][0] == 0; i++) {
            dp[i][0] = 1;
        }
        for (int i = 0; i < n && obstacleGrid[0][i] == 0; i++) {
            dp[0][i] = 1;
        }

        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (obstacleGrid[i][j] == 1){
                    // 是障碍物不能走
                    dp[i][j] = 0;
                }else {
                    dp[i][j] = dp[i-1][j] + dp[i][j-1];
                }
            }
        }
        return dp[m-1][n-1];
    }
}
